Im sooooooo confused?

Ok i had the implant removed on the 28th march 2011 had a period from the 28th until the 4th april... DTD with OH numerous times.. Aprils AF was due the 28th April didn't turn up and now May's AF was due today but hasn't shown up but I have been getting BFN on the tests and I have tried the one that tells you 4 days before your period is due.... could the implant removal be mucking me around? I really want to know where I stand so I can plan accordingly as this is driving me up the wall.....